Recently, heat-shrinkable plastic films made from a variety of resins are widely used for applications such as external packaging for improving the appearance of packaged goods, packaging for avoiding direct collision of contents, and label packaging for both of a protection of glass bottles or plastic bottles and indication of commercial products. Among these heat-shrinkable plastic films, stretched films made from polyvinyl chloride resin, polystyrene resin, polyester resin, polyolefin resin, or the like are used for the purpose of labeling, cap sealing or assembling packaging in various containers such as polyethylene terephthalate (PET) containers, polyethylene containers, and glass containers.
However, although excellent in shrinkage characteristics, polyvinyl chloride films pose problems of, in addition to low heat resistance, generating a hydrogen chloride gas during incineration, generating dioxins, and the like. In addition, use of polyvinyl chloride resin films as shrinkable labels for PET containers and the like also causes a problem that a label has to be separated from a container upon recycling the container. On the other hand, although excellent in finished appearance after shrinkage, polystyrene films are poor in solvent resistance, and thus suffering a disadvantage that an ink of a special composition has to be used upon printing. Additionally, polystyrene films need to be incinerated at high temperature and cause a problem of generating a large amount of black smoke along with foul smells during incineration.
Therefore, polyester films and polyolefin films, which have high heat resistance, are easy to incinerate, and are excellent in solvent resistance, have been widely utilized as shrinkable labels. The amount of use of polyester films and polyolefin films tends to increase as the distribution amount of PET containers increases. Further, general heat-shrinkable polyester films and general heat-shrinkable polyolefin films that are stretched at a high ratio in the width direction and greatly shrunk in the width direction (namely, heat-shrinkable films whose main shrinkage direction is the width direction) are widely utilized (Patent Document 1).    Patent Document 1: Japanese Unexamined Patent Publication No. 2004-74426